In an extrusion-based additive manufacturing system, a 3D part is printed from a digital representation by extruding a flowable part material to build up the part in a layer-by-layer manner. A filament is fed to an extrusion nozzle in the printer head where it is melted, and then ejected onto a substrate in fluid form while the printer head moves in a horizontal plane to trace out a layer. The extruded material fuses to previously deposited material, and solidifies quickly.
The printer head on such a tool should be compact, so as to maximise the size of the object that can be produced, and lightweight, so as to enable it to be rapidly moved and accurately positioned without adverse inertia effects. Providing multiple extrusion nozzles on the printer head allows for improved flexibility, such as the ability to readily change extrusion materials or colours, without nozzle removal and replacement. However, prior designs have not been optimal, and there is a need for a printer head with improved flexibility, which is not compromised by excessive weight, size or structural complexity.
One of the advantages of extrusion-based additive manufacturing is that the capital and operating costs of the tools are lower than for competing technologies, such as stereolithography. However, it has previously been considered that high resolution must be sacrificed in using this technology in order to obtain reasonable operating speeds. There is therefore an unmet need for an extrusion-based additive manufacturing tool that is able to offer both higher resolution and faster operating speed. It is an object of the present invention to address these needs or, more generally, to provide an improved 3D printer.